package trees;

public class ClimbStairs {
    public int climbStairs(int n) {
        // dp[n]对应的就是有n种方法
        // dp[n] = dp[n-1] + dp[n-2]

        if (n == 1 || n == 2) {
            return n;
        }

        int[] dp = new int[n + 1];
        dp[1] = 1;
        dp[2] = 2;

        for (int i = 3; i <= n; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }

        return dp[n];
    }
}
